* [fileprovider] Update for Xcode 12 beta 6
This was quite noisy. Apple removed all API marked as
`FILEPROVIDER_API_AVAILABILITY_V3`.
```
```
Most were bound but they were (majority) decorated with `[NoiOS]` and
`[NoMac]` so they did not generated any bindings.
A few of them were modified or just became macOS-only.
Deprecation warnings also needed to be updated.
Sebastien Pouliot